1 April 2009

Task Order No. 3003 Task 2, Subtask b, Item 1

Technical Directive No. 7

Summary of Frequency of Overfill Protection Device Data from State Databases

E2 Inc. compiled available data on overfill protection devices from state databases (obtained 

from the results of TO3003, TDD 5) into an Excel file (attached as an Appendix to this 

summary) and calculated overall frequency totals and percentages from these data. This report 

provides a summary of key results and includes the following appendices:

1. Tanks Currently in Use

2. Tanks in Temporary Closure

Methods

Twenty-three state databases were investigated to determine the information they contained 

regarding overfill protection devices (Table 1). Ten states had adequate data to provide 

information specific to the frequency of use of the three overfill devices: ball float valves, 

automatic shutoff devices, and overfill alarms. The following general rules were applied to data:

 only data from the 10 states that had adequate data on the three overfill devices were

utilized;

 databases that reported device types other than the three specified in this analysis were 

categorized as “other” types of devices; 

 blank entries in the database were considered “unknown”; and

 every overfill device was counted, even in cases where there was more than one device

noted for a specific tank or the tank was exempt from requiring a device.

Seven states had information indicating whether or not tanks had overfill devices, but inadequate 

data to determine what types of devices were used. Six states did not have any information 

regarding the use of overfill devices (Table 1).

Table 1: State Database Information for Overfill Protection Devices

Adequate Data for This 

Analysis

Inadequate Data for This 

Analysis

No Data

State Region State Region State Region

New York

Virginia

Florida

North Carolina

South Carolina

Arkansas

Texas

Missouri

Utah

Washington

2

3

4

4

4

6

6

7

8

10

Massachusetts

New Hampshire

Maryland

Georgia

Mississippi

Tennessee

Montana

1

1

3

4

4

4

8

Michigan

Ohio

Wisconsin

Nebraska

Hawaii

Nevada

5

5

5

7

9

9
2 April 2009

Results for Tanks Currently in Use (Appendix 1)

For the 10 states that had adequate data for this analysis, total and percentage values for 

automatic shutoff valves, ball float valves, overfill alarms, and other devices at tanks currently in 

use are provided in Table 2. Ninety-four percent of all tanks currently in use employ some type 

of overfill device. Automatic shutoff valves and ball float valves are used with the highest 

frequency, each representing 39 percent of overfill protection devices on all tanks currently in 

use.

Table 2: Total and Percentage Values of Overfill Devices for Tanks Currently in Use

Tanks Automatic 

Shutoff 

Valve

Ball Float 

Valve

Overfill 

Alarm

Other 

Device

Tanks with 

Overfill 

Device

Total Number 184,193 71,749 71,287 25,731 36,790 173,068

Percentage of total tanks 39% 39% 14% 20% 94%

Percentage of total tanks 

with an overfill device

41% 41% 15% 21%

Results for Tanks in Temporary Closure (Appendix 2)

For the 10 states that had adequate data for this analysis, total and percentage values for 

automatic shutoff valves, ball float valves, overfill alarms, and other devices at tanks in 

temporary closure are provided in Table 3. Results indicate that 73 percent of all tanks in 

temporary closure employ some type of overfill device. Automatic shutoff valves are used most 

often, installed in 34 percent of the tanks in temporary closure.

Table 3: Total and Percentage Values of Overfill Devices for Tanks in Temporary Closure

Tanks Automatic 

Shutoff

Valve

Ball Float 

Valve

Overfill 

Alarm

Other 

Device

Tanks with 

Overfill 

Device

Total Number 12,227 4,140 2,669 632 3,028 9,461

Percentage of total tanks 34% 22% 5% 25% 77%

Percentage of total tanks 

with an overfill device

44% 28% 7% 32%